[worklets] Introduce ThreadedWorkletMessagingProxy and AnimationWorkletMessagaingProxy.

third_party/WebKit/Source/modules/compositorworker/AnimationWorkletMessagingProxy.cpp

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "modules/compositorworker/AnimationWorkletMessagingProxy.h"
+
+#include "core/workers/ThreadedWorkletObjectProxy.h"
+#include "modules/compositorworker/AnimationWorkletThread.h"
+
+namespace blink {
+
+AnimationWorkletMessagingProxy::AnimationWorkletMessagingProxy(ExecutionContext* executionContext)
+    : ThreadedWorkletMessagingProxy(executionContext)
+{
+}
+
+AnimationWorkletMessagingProxy::~AnimationWorkletMessagingProxy()
+{
+}
+
+std::unique_ptr<WorkerThread> AnimationWorkletMessagingProxy::createWorkerThread(double originTime)
+{
+    return AnimationWorkletThread::create(loaderProxy(), workletObjectProxy());
+}
+
+} // namespace blink